Spina Bifida

Spina bifida is a congenital neural tube defect caused by problems with the early development of the spinal cord.

The main defect of spina bifida is the failure of closure of the vertebral column (the bony column surrounding the spinal cord) during embryogenesis. Embryogenesis refers to the stages of a developing embryo after fertilization of the egg by the sperm. Without closure of the neural tube, which normally occurs by 28 days, the spinal cord fails to obtain the usual protection of the vertebrae, and is left open to either mechanical injury or invasion by infection.

Spina bifida is one of a number of neural tube defects. The neural tube is the name for the very primitive structure which is formed during fetal development, and which ultimately becomes the spinal cord and the brain. Other neural tube defects include anencephaly, in which the cerebral hemispheres (sites for all higher intellectual functioning) are absent.

Spina bifida occurs in 1 in 1000 births to North American whites, but in less than 1 in 3,000 births to blacks. In some areas of Great Britain, the occurrence is as high as 1 in 100 births. Women who have a child with spina bifida are at a slightly higher risk of having children with spina bifida in subsequent pregnancies. Women who have spina bifida or have had a previous pregnancy affected by any type of neural defect are also at a greater recurrence risk.

Most cases of spina bifida are apparent at birth. Affected pregnancies can often be detected by ultrasound. Various radiographic techniques are helpful, such as CT (computed tomography) scans, MRI (magnetic resonance imaging), and ultrasonography.